Stemless prosthesis anchor components, methods, and kits

ABSTRACT

A method of implanting a shoulder prosthesis assembly is provided where the method includes advancing by rotation a base member, that includes a cylindrical member and a helical structure, into a resection face of a humerus of a patient such that the helical structure is submerged in and engages cancellous bone of and does not extend distally of an epiphysis of the humerus, the cylindrical member being accessible at the resection face of the humerus when the base member is so advanced; advancing a locking device into the base member until at least one elongate member spans a space between adjacent portions of the helical structure to contact the cancellous bone in the space; and inserting a retention portion of a reverse articular insert into the cylindrical member of the base member to directly connect the reverse articular insert with the cylindrical member of the base member.

INCORPORATION BY REFERENCE TO ANY PRIORITY APPLICATIONS

Any and all applications for which a foreign or domestic priority claimis identified in the Application Data Sheet as filed with the presentapplication are hereby incorporated by reference under 37 C.F.R. § 1.57.

BACKGROUND OF THE INVENTION Field of the Invention

The present disclosure relates to a stemless prosthesis anchor componentof a joint prosthesis that can be coupled with a concave articular bodysuch as is used in reverse shoulder arthroplasty.

Description of the Related Art

Skeletal joints have a variety of configurations providing for a widerange of smooth movement of two or more bones relative to each other.For example, in a shoulder joint, the head of the humerus interacts withthe glenoid cavity of the scapula in a manner similar to a “ball andsocket” joint. Over time, it may become necessary to replace a joint,such as the shoulder joint, with a prosthetic joint. The prostheticjoint can include components mounted to one, two or more than two bonesat the joint. For example, the prosthetic joint can include a humeralcomponent, a glenoid component or both a humeral and a glenoidcomponent.

Conventional humeral components include a humeral head coupled with astemless humeral anchor to minimize bone loss and other disadvantages ofthe use of humeral anchors with stems. Stemless humeral anchors can becoupled with anatomic articular bodies and with reverse articularbodies. An anatomic articular body has a convex articular surface thatfaces the glenoid portion of the joint. A reverse articular body has aconcave articular surface that faces the glenoid portion.

Reverse articular bodies conventionally are connected to an intermediatecomponent that is connected to a stemless humeral anchor. Thisintermediate component, which is sometimes called a tray, adds thicknessto the assembly and can therefore limit how close the humerus can beplaced to the glenoid following a reverse shoulder implant procedure.While a stemless humeral anchor could be inset into the epiphysis of thehumerus inferior of the resection plane to provide a larger range of theposition of the humerus to the glenoid, inset positioning can compromisethe integrity of the fixation into the humerus.

SUMMARY OF THE INVENTION

Accordingly, there is a need for additional stemless shoulder assembliesthat enhances a surgeon's ability to position the humerus relative tothe scapula following implantation of stemless humeral anchors. A widerrange of possible positions can allow for better soft tissue tensioningwhich can help to reduce, e.g., minimize, a risk of dislocation of theshoulder joint or acromion fractures. Such assemblies preferably includecomponents designed to preserve bone in initial implantation whileenhancing initial pull-out and back-out resistance. Preferably enhancedinitial dislodgement resistance will also provide excellent long termfixation.

In one embodiment, a shoulder assembly is provided that includes a basemember and a locking device. The base member includes a collar, ahelical structure, and a first pathway projecting distally of thecollar. The helical structure extends from the collar in a distaldirection. The first pathway projects distally of the collar and throughthe helical structure. The first pathway is disposed adjacent to aninner periphery of the helical structure. The first pathway is generallytransverse to the helical structure and extending in a space betweensuccessive portions of the helical structure. The locking device has aproximal support and a first arm that projects distally of the proximalsupport. The first arm is configured to be disposed in the first pathwaythat projects distally of the collar when the proximal support isdisposed adjacent to the collar. The first arm is disposed through bonein the space between successive portions of the helical structure whenthe shoulder assembly is implanted. A cylindrical member is disposed insome embodiment on an end of the base opposite the helical structure,e.g., away from the collar. The cylindrical member configured todirectly engage a reverse shoulder insert.

In some embodiments, a kit can be provided that includes a shoulderassembly as described above, an anatomic articular component, and areverse articular component. The anatomic articular component ismateable with the shoulder assembly. The anatomic articular componenthas a convex articular surface adapted to articulate with a concavesurface of or on a scapula of a patient. The reverse articular componentis mateable with the shoulder assembly. The reverse articular componentcomprises a concave articular surface adapted to articulate with aconvex surface on a scapula of a patient. The reverse articularcomponent includes a retention portion for mating the reverse articularcomponent directly to the base member, e.g., at a cylindrical portionthereof.

In another embodiment, a prosthesis assembly is provided that includes abase member that has a helical structure and a first pathway. The basemember has a first end and a second end. The helical structure extendsbetween the first end and the second end. The first end comprises adistal or medial end in some applications. The second end comprises aproximal end or a lateral end in some applications. The first pathway isaccessible from the second end and is directed toward the first endthrough the helical structure. The first pathway is located inward of anouter periphery of the helical structure, e.g., adjacent to an innerperiphery of the helical structure. The first pathway is generallytransverse to the helical structure. The first pathway extends in aspace between successive portions of the helical structure. Theprosthesis assembly includes a locking device that has a support memberand a first arm that projects away from the support member. The firstarm is configured to be disposed in the first pathway when the supportmember is disposed adjacent to the second end of the base member. Thefirst arm is disposed through bone in the space between successiveportions of the helical structure when the prosthesis assembly isimplanted. The prosthesis assembly can be configured such that thelocking device engages with the base member with a first side disposedadjacent to the base member and a second portion disposed adjacent to areverse articular component engaged with the base member.

The prosthesis assemblies discussed herein can be mated with a proximalhumerus. The prosthesis assemblies discussed herein can be mated withother anatomy as well, such as a glenoid of a scapula. The prosthesisassemblies discussed herein can be mated with a bone adjacent to anelbow joint, such as a distal humerus or a proximal radius. Theprosthesis assemblies discussed herein can be mated with a bone adjacentto a wrist joint, such as a distal radius. The prosthesis assembliesdiscussed herein can be mated with a bone adjacent to the hip, such as aproximal femur. The prosthesis assemblies discussed herein can be matedwith a bone adjacent to a knee joint, such as a distal femur or aproximal tibia. The prosthesis assemblies discussed herein can be matedwith a bone adjacent to an ankle joint, such as a distal tibia or aproximal talus. The description of the uses of the assemblies disclosedherein in connection with these and other bones is supplemented byreference to US application no. PCT/US2017/038843, which is herebyincorporated herein by reference.

In another embodiment, a method of implanting a prosthesis is provided.The method includes advancing by rotation a base member into a boneadjacent to a joint. The bone can include an epiphysis of a humerus of apatient. The bone can include a glenoid of a scapula of a patient. Thebone can include a distal portion of a humerus adjacent to an elbowjoint. The bone can include a proximal portion of a radius adjacent toan elbow joint. The bone can include a distal portion of a radiusadjacent to a wrist joint. The bone can include a proximal portion of afemur adjacent to a hip joint. The bone can include a distal portion ofa femur adjacent to a knee joint. The bone can include a proximalportion of a tibia adjacent to a knee joint. The bone can include adistal portion of a tibia adjacent to an ankle joint. The bone caninclude a proximal portion of a talus adjacent to an ankle joint. Thebase member comprising a helical structure configured to engagecancellous bone of the epiphysis or other portion of any of the bonesset forth above. The helical structure can be disposed about asubmergible portion that, in use, is submerged into the cancellous boneinferior of a resection plane of the epiphysis. An external surfacedisposed superior to the submergible portion can have a bone interfaceportion advanced into engagement with an exposed face of the humerus. Anexposed portion of the base member can be disposed superior to the boneinterface portion. A locking device is advanced by linear translationinto the base member. The locking device can be inserted into acylindrical member disposed at the exposed portion of the base member.An opening into the cylindrical member can comprise a superior end ofthe exposed portion of the base member. The locking device has at leastone arm adapted to span a gap between adjacent portions of the helicalstructure. The locking device contacts the cancellous bone in the gap. Areverse articular component can be selected for a patient and can beinserted into direct engagement with the concave member of the basemember.

In another embodiment, a shoulder assembly is provided that includes abase member and a reverse insert. The base member has a submergibleportion, an exposed portion, and a cylindrical member extending alongthe submergible portion. The submergible portion has a helicalstructure. The cylindrical member extends from the submergible portionto the exposed portion. The reverse insert has an articular portion anda retention portion. The articular portion includes a concave surfaceconfigured to articulate over a glenosphere. The (99). The cylindricalmember and the retention portion are configured to provide for directcoupling between the reverse insert and the base member.

In another embodiment a prosthesis assembly is provided that includes abase member and a locking device. The base member has a first end and asecond end. The base member has a cylindrical member that is configuredto receive and directly couple with a reverse insert. The base memberhas a helical structure that extends between the first end and thesecond end. The base member has a first pathway that is accessible fromthe second end and that is directed toward the first end through thehelical structure. The first pathway is located adjacent to an innerperiphery of the helical structure. The first pathway is generallytransverse to the helical structure and extends in a space betweensuccessive portions of the helical structure. The locking device has asupport member and a first arm projecting away from the support member.The first arm is configured to be disposed in the first pathway when thesupport member is disposed adjacent to the second end of the basemember. The first arm is disposed through bone in the space betweensuccessive portions of the helical structure when the prosthesisassembly is implanted.

In another embodiment a method of implanting a prosthesis is provided inwhich a base member that has a cylindrical member is advanced byrotation into a humerus of a patient such that a helical structure ofthe base member is submerged in and engages cancellous bone of and doesnot extend distally of an epiphysis of the humerus. The cylindricalmember is accessible at a resection face of the humerus when the basemember is so advanced. A locking device is advanced into the base memberuntil at least one elongate member spans a space between adjacentportions of the helical structure to contact the cancellous bone in thespace. A retention portion of a reverse articular insert is insertedinto the cylindrical member of the base member to directly connect thereverse articular insert with the cylindrical member of the base member.

Any feature, structure, or step disclosed herein can be replaced with orcombined with any other feature, structure, or step disclosed herein, oromitted. Further, for purposes of summarizing the disclosure, certainaspects, advantages, and features of the inventions have been describedherein. It is to be understood that not necessarily any or all suchadvantages are achieved in accordance with any particular embodiment ofthe inventions disclosed herein. No aspects of this disclosure areessential or indispensable.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects and advantages are described belowwith reference to the drawings, which are intended to illustrate but notto limit the inventions. In the drawings, like reference charactersdenote corresponding features consistently throughout similarembodiments. The following is a brief description of each of thedrawings.

FIG. 1 is a schematic view of a glenohumeral (shoulder) joint during anearly stage of a shoulder surgery;

FIG. 1A is a schematic view of reverse shoulder assembly placed in ashoulder joint;

FIG. 1B is a perspective view of one embodiment of a stemless shoulderassembly shown mounted in a humerus, and further illustrates a kitincluding anatomic and reverse shoulder articular components;

FIG. 1C is a perspective view of one embodiment of a stemless shoulderassembly shown mounted in a humerus, and further illustrating a kitincluding reverse shoulder articular components;

FIG. 2 is an exploded view of the stemless shoulder assembly shown inFIG. 1;

FIG. 2A is an exploded view of one of many combinations of stemlessshoulder assemblies wherein the shoulder assembly includes a base memberconfigured to be advanced into cancellous bone of the humerus and to beengaged directly with a reverse articular component;

FIG. 3A is a side view of the base member of FIG. 2;

FIG. 3B is a top view of the base member of FIG. 2;

FIG. 3C is a cross-sectional view of the base member of FIG. 2 taken atsection plane 3C-3C;

FIG. 3D is a cross-sectional view of the base member of FIG. 2 taken atsection plane 3D-3D;

FIG. 4 is a side view of one embodiment of a locking component, which isa component configured to control, e.g., reduce or eliminate and/orcontrol rotation of a base member or of a helical structure of aprosthesis assembly;

FIG. 5 is a top, proximal side, or medial side view of the lockingcomponent of the FIG. 4;

FIG. 6A is a detail view of one embodiment of an engagement feature thatcauses the locking component of FIG. 4 and the base member of FIGS. 3Aand 3B to be engaged;

FIG. 6B is a detail view of another embodiment of an engagement featurethat causes the locking component and the base member to be engaged at alocation within the helical structure;

FIG. 7 is a cross-sectional view of the stemless shoulder assembly ofFIG. 2 with the assembly disposed in the humeral head;

FIG. 7A is a schematic view showing the base member of the kit of FIG.2A disposed in a resected humeral head;

FIGS. 8-16 illustrate various methods for implanting a prosthesisassembly of FIGS. 1-7 into a portion of a bone;

FIG. 16A shows a detail view of a first manner of securing a reversearticular component to a concave member of a low profile base member;

FIG. 16B shows a detail view of a second manner of securing a reversearticular component to a concave member of a low profile base member;

FIG. 17 is a side view of the stemless shoulder assembly of FIG. 2coupled with an anatomic articular component of the kit illustrated inFIG. 1;

FIG. 18 shows a reverse shoulder prosthesis including a reversearticular component coupled with the humerus and a convex glenoidcomponent, sometimes referred to as a glenoid sphere, coupled with thescapula;

FIG. 18A is a side view of the stemless shoulder assembly of FIG. 2coupled with a reverse articular component of the kit illustrated inFIG. 1;

FIG. 18B is a side view of the stemless shoulder assembly assembled fromthe kit of FIG. 1C with a reverse articular component coupled directlywith a stemless anchor;

FIG. 18C shows an exploded view of shoulder assembly including a spacer,the shoulder assembly being assembled from the kit of FIG. 1C;

FIGS. 19A and 19B show comparative pull out and lever out performance ofan embodiment as disclosed herein compared to a conventional stemlessimplant.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

While the present description sets forth specific details of variousembodiments, it will be appreciated that the description is illustrativeonly and should not be construed in any way as limiting. Furthermore,various applications of such embodiments and modifications thereto,which may occur to those who are skilled in the art, are alsoencompassed by the general concepts described herein. Each and everyfeature described herein, and each and every combination of two or moreof such features, is included within the scope of the present inventionprovided that the features included in such a combination are notmutually inconsistent.

This application is directed to shoulder implants that provide greatercontrol of the soft tissue tension around the joint followingimplantation. The improvements herein enable a patient to have anappropriate level of tension in the soft tissue to provide good range ofmotion while reducing the risk of dislocation of the shoulder joint oracromion fracture following surgery. FIG. 1 illustrates a shoulder jointthat includes a humerus H and a glenoid G of a scapula Sc. Soft tissuearound the joint is shown schematically as well. In an early part of aprocedure for repairing the shoulder joint an incision I is made in thesoft tissue. The incision I provides access to the head of the humerus Hand the glenoid G. Greater access is often provided by dislocating thenatural joint. Typically the humerus H is resected to remove the naturalarticular component of the humerus H. FIG. 1A shows the humerus Hresected and a conventional reverse shoulder joint assembly implanted inthe humerus H and the glenoid G. Specifically, an anchor is insertedinto the resected humerus H and a concave articular component 12 ismounted to the anchor. The anchor would be located in the humerus H inFIG. 1A and thus not visible but could be a conventional stemmed anchor.The concave articular component 12 is indirectly mounted to the anchor10 by an intervening tray 14. The motion of the prosthetic shoulderjoint is provided between the concave articular component 12 and aglenosphere 16 that is mounted to the glenoid G. The prosthesisillustrated in FIG. 1A is a reverse shoulder prosthesis because in thenatural shoulder joint the glenoid G has a concave shape and the head ofthe humerus H has a convex shape.

The arrow 20 in FIG. 1A illustrates an aspect of the range of motion ofthe humerus H relative to the scapula Sc. This motion and a risk ofdislocation following surgery are a function of how much tension isplaced on the soft tissue around the humerus H and the scapula Sc whichis related to the location of the center of the concave articularcomponent 12. The location of the center of the concave articularcomponent 12 is adjustable over a range. However, one limit on theability to adjust soft tissue tensioning is the minimum height of theconcave articular component from the resection surface of the humerus H.The minimum dimension could be less, providing a greater range ofadjustment of the soft tissue tensioning if the tray 14 could beeliminated or the height of the concave articular component 12 from theresection plane otherwise reduced.

FIG. 1B shows an embodiment of a shoulder arthroplasty kit 80 thatincludes a shoulder assembly 100. The kit 80 can be combined with ashoulder arthroplasty kit 80A discussed below. The kit 80 is configuredfor allowing a surgeon to provide an anatomic arrangement or a reversearrangement. The kit 80A can be used if during the procedure (or before)the patient is deemed to benefit from an initial reverse procedure. Thekits 80, 80A can be packaged together or separately.

The kit 80 can include one or both of an anatomic articular component 84and a reverse articular component 88. The anatomic articular component84 can comprise a one-piece structure including a convex articularsurface 90 disposed on a proximal or lateral side and a taperedprojection 92 disposed on a distal side thereof. The reverse articularcomponent 88 can comprise a two-piece structure including a tray 94 andan insert 96. In other embodiments, the articular component 88 has aone-piece configuration. In other embodiments, the articular component88 has a monolithic configuration. Monolithic embodiments can comprise aone material configuration. Monolithic embodiments can comprise two ormore material. The insert 96 can mate with the tray 94 in any suitablemanner, such as by interference fit or snap fit. The tray 94 can includea tapered projection 98. In other embodiments the tray 94 can beeliminated such that the insert 96 can mate directly with a shoulderassembly 100A discussed below. FIGS. 17 and 18 show a glenoid sphere 99that can be included in some embodiments of the kit 80. Such a variationof the kit 80 also can include corresponding components for anchoringthe glenoid sphere 99 in or to a glenoid. The insert 96 is shown in justone embodiment in which the insert 96 is angled, such that a planeintersecting the medial side of the insert 96 is at an angle to the sidethat faces the shoulder assembly 100 providing a thicker superiorportion. In other embodiments the insert 96 is angled, such that a planeintersecting the medial side of the insert 96 is at an angle to the sidethat faces the shoulder assembly 100 providing a thicker inferiorportion. In other embodiments the insert 96 is not angled, such that theplane intersecting the medial side of the insert 96 is substantiallyparallel to the side that faces the shoulder assembly 100 as shown inthe kits of FIGS. 1C and 1 n the combinations of FIGS. 2A and 18C andthe assembly of FIG. 18B.

FIG. 1B shows the shoulder assembly 100, as further described below inconnection with FIGS. 2-7, implanted in an exposed face F of a humerusH. The assembly 100 has a recess 102 in which further components of aprosthetic shoulder joint can be secured. The assembly 100 and therecess 102 enable the humerus H to be fitted with either an anatomicalshoulder by receiving the anatomic articular component 84, moreparticularly, the projection 92 or a reverse shoulder component 88 byreceiving the projection 98 either initially or as part of a revisionprocedure. Methods of using the kit 80 to implant the shoulder assembly100 as part of a shoulder prosthesis are discussed below in connectionwith FIGS. 8-16. FIGS. 19A and 19B illustrate the performance of certainembodiments compared to a prior art design. While incrementaldifferences in these embodiments and methods are discussed below, it isto be understood that features of each embodiment can be combined withfeatures of the other embodiments, as appropriate.

I. Humeral Shoulder Assemblies Having Rotation Control Locking Devices

FIGS. 1B and 7 show the shoulder assembly 100 applied to a shoulderjoint. FIG. 2A shows an exploded view of a shoulder assembly 100A thatis similar to the shoulder assembly 100 except as described differentlybelow. The description of the features of the shoulder assembly 100 thatare present in or consistent with the shoulder assembly 100A shall beincorporated into the description of shoulder assembly 100A even if notexplicitly repeated in connection therewith. The assembly 100 canprovide secure stemless connection to the humerus H. The shoulderassembly 100 provides for simple implantation because a base memberthereof can be directly threaded into cancellous bone without beingmated to another pre-placed base member. The shoulder assembly 100 canbe fully retained within a head h of the humerus H. FIG. 7 shows thatthe distal-most portion of the assembly 100 preferably can be disposedin the humeral head h. The assembly 100 does not have a stem or othermember that protrudes beyond the head h into a medullary canal of thehumerus. This approach is less invasive and simpler than proceduresinvolving placement of a stem in a medullary canal. In other embodimentsillustrated in part in FIG. 10 by the creation of a recessed surface shaving a depth accommodating a thickness of a proximal portion of theassembly 100, the assembly 100 may be recessed within the humeral headof the humerus H such that a proximal face 105 the assembly 100 is flushwith respect to a cut surface of the bone.

FIG. 2 shows that the assembly 100 includes a base member 104 and alocking device 108. The base member 104 is advanced into a bonystructure such as cancellous bone in use. As discussed further below abone surface may be exposed by resection or reaming, followed bythreading of the base member 104 into a newly exposed bone surface. Theassembly 100 also includes the locking device 108. The locking device108 includes a plurality of arms 110 (elongate members). In particular,the arms 110 extend outward or distal from proximal support 132. Thearms 110 can include a first arm, a second arm, and a third arm. Thearms 110 can be circumferentially spaced equal distances from eachother, e.g., about 120 degrees apart in one embodiment. In anothervariation, the arms 110 include three arms, with two of the three armsspaced 90 degrees from each other and a third arm spaced 135 degreesfrom one of the other two arms. The locking device 108 may include fouror more arms 110. If the arms 110 include four arms, the arms can becircumferentially spaced 90 degrees apart. If the arms 110 include twoarms, the arms can be circumferentially spaced 180 degrees apart. Thearms 110 are advanced through apertures 124 in the base member 104. Inone embodiment, it should be noted that the number of arms 110corresponds to an equal number of apertures 124. When so advanced, thearms 110 are disposed within the base member 104 in a manner that thearms 110 cross a space between portions, e.g., successive portions, ofthe base member 104. When so positioned, the arms 110 are also disposedwithin the bone. Thus, two zones of the arms 110 can cross successive oradjacent portions of the base 104 and an intervening portion of the arms110 can cross the bone in a space between the successive or adjacentportion of the base. In this position, the arms 110 control, e.g.,resist, rotation of the base member 104 relative to the bone such thatthe shoulder assembly 100 is secured against backing out of the boneupon implantation.

FIG. 2 also shows that the locking device 108 also includes a proximalsupport 132. The proximal support 132 is coupled with the arms 110 in amanner discussed further below. The proximal support 132 has a centralaperture 136 disposed within an inner periphery thereof and extendsoutward from the central aperture 136 to an outer periphery 135. Theinner and outer periphery of the proximal support 132 are received in arecess 140 formed in the base member 104. In one configuration therecess 140 and the proximal support 132 are configured such that a flushconnection is provided between the proximal support 132 and the proximalface of the base member 104. The proximal support 132 can be connectedto the base member 104 in an at least partially recessed position in theproximal face of the base member as discussed further below inconnection with FIG. 6A.

FIGS. 2 and 3B show that the proximal face of the base member 104 caninclude a raised inner portion 148 and a raised outer portion 152. Theouter raised portion 152 extends around an outer periphery 154 of thebase member 104. The raised portions 148, 152 are proximally orientedprojections relative to a recessed surface 156. The recessed surface 156can be disposed distally of one or both of the inner portion 148 and theouter portion 152. The raised inner portion 148 can define an aperturefor access into the recess 102, which is configured for mating witharticular components as discussed below. Each of the raised innerportion and the raised outer portion 148, 152 can comprises annularstructures. The recessed surface 156 can comprise an annular portion.The apertures 124 can be formed in the recessed surface 156. In oneembodiment the apertures 124 extend radially between the inner raisedportion 148 and the outer raised portion 152. The apertures 124 canextend from the inner raised portion 148 to the outer raised portion152. FIG. 2A shows that in one embodiment a raised outer portion 156Acan be raised to a much greater extent than the raised inner portion148. The raised outer portion 156A can be raised sufficiently to receivean inferior portion of an insert 96A as discussed further below. Theraised outer portion 156A can overlap an inferior peripheral surface ofthe insert 96A to engage the insert as discussed below.

FIG. 3B shows that the proximal face of the base member 104 also caninclude a tool interface 158 that enables the base member to be advancedby an inserter into bone, as discussed below in FIG. 14. The toolinterface 158 includes three notches in an inward side of the outerraised portion 152. In other embodiments, the tool interface 158 caninclude apertures in the recessed surface 156, notches in the innerraised portion 148, projections from any surface of the proximal face ofthe base member 104 or any combination of these features. Also, the toolinterface 158 can provide access for a removal tool to engage thelocking device 108. As discussed below, the locking device 108 includesa spring arm 168 and a removal tool can be applied at the tool interface158 to compress the arm 168 to disengage the locking device from thebase member 104. In some cases, an inserter tool can engage one or moreapertures 124 in the base member 104 upon insertion.

One or more structures for securing the locking device 108 to the basemember 104 or to the low profile base member 104A can be provided asdiscussed further below. For example the locking device can have anengagement feature 164 disposed on the proximal support 132 that isadapted to engage a corresponding feature on the proximal face of thebase member 104 or on the low profile base member 104A. The engagementfeature 164 can include an actuatable member that can move into a secureposition relative to the recess 140 of the base member 104 or the lowprofile base member 104A. As discussed below in connection with FIGS. 5and 6A, the engagement features 164 can include a spring arm 168 toengage an overhang of the recess 140. As shown in FIG. 2, one embodimentcomprises a plurality of actuatable members, e.g., a plurality of springarms 168. The spring arms 168 can be spaced apart, e.g., providing equalangle separation between adjacent spring arms 168. In one embodiment,the number of spring arms 168 matches the number of arms 110. Eachspring arm 168 can be spaced apart from each arm 110 as discussedfurther below.

In another embodiment, a serration 172 is provided between the arms 110of the locking device 108 and the base member 104 or the low profilebase member 104A as discussed in greater detail below in connection withFIG. 6B. The serration 172 is an example of a one-way connection thatcan be provided between the arms 110 and the base member 104. Otherone-way connections can be provided in addition or in place of theserration 172, such as a ratchet, a barb, or one or more spring arms.

FIGS. 2-3B show further details of embodiments of the base member 104and the low profile base member 104A. In some embodiments, the basemember 104 can include various features described in PCT publicationWO2016/094739, the entirety of which is hereby incorporated by referenceherein. The base member 104 has a first end 204, a second end 208 and abody 212 that extends between the first end 204 and the second end 208.The base member 104 can comprise a length L between the first end 204and the second end 208 that is less than a dimension of an articularsurface of typical epiphysis to a medullary canal of a typical humerus.The base member 104A can comprise a length L between the first end 204and the second end 208A that is less than a dimension of a correspondingdimension from the first end 204 of the base 104 of the assembly 100 tothe superior edge of the tray 94. FIGS. 18A and 18B show that the lengthL of the low profile base member 104A can be greater than that of thebase member 104. But, the shoulder assembly 100A is able to provide anoverall lower profile to an associated articular surface as discussedfurther below. The first end 204 can be disposed within the epiphysiswhen the second end 208 is at a surface of the bone, as shown in FIG. 7.The second end 208 can be disposed at or on a superior medial resectionplane of a humerus while the first end 204 is well within the epiphysis.This enables the first end 204 to stop short of a medullary canal of thehumerus when the base 104 is fully implanted, which allows the bonebetween the first end 204 and the medullary canal to remain unalteredand also simplifies the procedure to the extent that any normal accessto and preparation of the medullary canal is not needed. The second end208A is generally higher above the resection plane of the humerus thanis the second end 208 as shown by comparison of FIGS. 7 and 7A by virtueof a cylindrical member 908 disposed at the superior end of the base104A. The additional height of the cylindrical member 908 of the base104A enable the base 104A to directly receive and engage an inferiorportion on an insert 96 as discussed further below. In variousembodiments, the length L can be between about 15 mm and about 30 mm,between about 18 mm and about 25 mm, between about 18 mm and about 24mm, between about 21 mm and about 27 mm, between about 24 mm and about29 mm, or between about 30 mm and 40 mm. The length L can be about 18mm, about 21 mm about 23 mm, about 24, mm about 26 mm about 29 mm, andabout 34 mm. In one approach, at least a portion of the assembly 100 orthe shoulder assembly 100A is patient specific. For example, the lengthL can be defined for a specific patient based on pre-operative planning,such as using two dimensional or three dimensional imaging. The basemember 104 or the low profile base member 104A can thereafter bemanufactured for that patient based on the determined dimension L.

The base member 104 can include a collar 220 and a helical structure224. The helical structure 224 is disposed about a cylindrical portion260 of the body 212 of the base member 104. In some embodiments, thehelical structure 224 extends directly from the body 212 and may beconsidered threads of the body 212. The helical structure 224 caninclude one or a plurality of threads, e.g., two, three, four, or morethreads, disposed between the first end 204 and the second end 208. Thethreads can start adjacent to the first end 204 and extend toward, e.g.,entirely to the second end 208. FIG. 3A shows that the threads or otherhelical structure 224 can end at or adjacent to the collar 220. Thethreads or other helical structure 224 can have inner portions 240disposed at or on the body 212 about the recess 102 and outer portions244 disposed along the periphery of the base 104. FIG. 3A shows that thehelical structure 224 has a width defined as the distance between theinner and outer portions 240, 244 that is large, e.g., comprising morethan one-quarter of, e.g., about one-third of, the width of the base 104at a given location. These large threads or other helical structure 224ensure large purchase in the bone. Large purchase provides strongresistance to pullout even prior to any bone ingrowth into the surfacesof the shoulder assembly 100. Generally one or more surfaces of theshoulder assembly 100 that are in direct contact with bone may betextured e.g., coated or layered with a porous material in order toaccelerate tissue ingrowth such as bony ingrowth Therefor good initialresistance to pull-out is advantageous for the patient. At least oneturn of a thread or other helical structure 224 completely surrounds therecess 102, e.g., by completely surrounding the body 212, in someembodiments.

The body 212 surrounds the recess 102, which is configured to mate withan articular component, such as humeral head or a glenoid sphere. In oneembodiment, the body 212 includes a cylindrical portion 260 within whichthe recess 102 is disposed. The cylindrical portion 260 can have anysuitable outside configuration, such as including a textured surfacethat is well suited to encourage bony ingrowth. The cylindrical portion260 can include a generally tapered profile in which a portion at oradjacent to the first end 204 of the base member 100 has a first widthand a portion at or adjacent to the second end 208 of the base member100 can have a second width, the second width being greater than thefirst width. In some embodiments, the cylindrical portion 260 isgenerally rounded and formed a blunt but tapered profile. Thecylindrical portion 260 can have a flat distal surface in someembodiments.

FIG. 7 shows that the cylindrical portion 260 can include a plurality oflayers. For example, an inner layer 264 can be disposed adjacent to therecess 102. The inner layer 264 can include the surface surrounding therecess 102 and can extend away from that surface toward an outer surfaceof the cylindrical portion 260. In one embodiment an outer layer 268 canbe disposed adjacent to the outer surface of cylindrical portion 260.The outer layer 268 can extend from the external surface of thecylindrical portion 260 toward the recess 102. In one embodiment, theouter layer 268 is formed directly on the inner layer 264 although otherarrangements are possible as well. The outer layer 268 can be a porousstructure that is suitable for bony ingrowth.

FIG. 7 also shows that a tool interface 272 can be disposed at oradjacent to the first end 204 of the base member 104. The tool interface272 can include a threaded portion that can mate with a delivery tool,as discussed further below. A lumen 276 can be provided at the first end204 such that access can be provided from the first end 204 through thewall of the cylindrical portion 212 into the recess 102. The lumen 276and recess 102 together provide access for a K-wire or other guidingdevice such that implanting the base member 104 can be controlled in anappropriate manner.

The collar 220 can be disposed at or can comprise the second end 208 ofthe base member 104. The collar 220 can have a transverse width, e.g., adiameter that is suitable for a given condition. For example, thediameter of the collar 220 can be selected such that the entire outerperiphery of the base 104 is within the bone exposed by resection and/orrecessed into such an exposed bone portion, e.g., as illustrated inFIGS. 8-12. The diameter of the cylindrical member 908 can be selectedsuch that the entire outer periphery of the low profile base member 104Ais within the bone exposed by resection and/or recessed into such anexposed bone portion, e.g., as illustrated in FIGS. 7A and 14A andcorresponding descriptions herein. In some embodiments the collar 220 orthe cylindrical member 908 has a diameter of more than about 25 mm andless than about 60 mm. The collar 220 or the cylindrical member 908 canhave a diameter of between about 30 mm and about 45 mm. The collar 220or the cylindrical member 908 can have a diameter of about 33 mm in oneembodiment. The collar 220 or the cylindrical member 908 can have adiameter of about 42 mm in one embodiment. Making the collar 220 or thecylindrical member 908 as large as possible within such bounds providesfor better load transfer between the collar 220 or the cylindricalmember 908 and the humerus H. In one approach, the diameter of thecollar 220 or the cylindrical member 908 can be defined for a specificpatient based on pre-operative planning, such as using two dimensionalor three dimensional imaging. The base member 104 or the low profilebase member 104A can thereafter be manufactured for that patient basedon the determined diameter of the collar. For example, the diameter ofthe collar 220 or the cylindrical member 908 can be selected such thatthe collar covers the cortical rim exposed by resection. The collar 220or the cylindrical member 908 can attach to or can be integrally formedwith the cylindrical portion 260 of the body 212. In one embodiment thecollar 220 or the cylindrical member 908 comprises a transverse flange290 that extends outward of the recess 102 that is also disposed at thesecond end 208. An inner portion of the flange 290 can be disposedadjacent to the recess 102 and can include the inner raised portion 148.An outer portion of the flange 290 can be disposed outward of the innerportion. The flange 290 can define the proximal face of the base member104 or of the low profile base member 104A. The flange 290 canaccommodate the proximal support 132 of the locking device 108. FIG. 6Ashows that in some embodiments, the flange 290 can at least partiallysurround a space 294 disposed therein to receive a portion of thelocking device 108. The space 294 can be an annular recess locatedproximal of the recessed surface 156 and between the inner portion 148and the outer portion. The space 294 can be bounded by an inner edge ofthe outer portion 152 and an outer edge of the inner portion 148.Comparing FIGS. 2 and 2A, the space 294 can be seen to be much deeper inthe low profile base member 104A such that the space 294 can accommodatean inferior portion of the insert 96 as discussed further below. Theflange 290 can engage the spring arm 168 of the locking device 108 inthe space 294 such that the locking device 108 will not be inadvertentlydisengaged from the base 104 or from the low profile base member 104Aand protrude from or be removed from the space 294.

FIGS. 2, 2A, and 7 show that in some embodiment, the shoulder assembly100 and the shoulder assembly 100A includes a pathway 300 that projectsdistally of the collar 220. The pathway 300 can comprise a firstpathway. The shoulder assembly 100 or the shoulder assembly 100A caninclude a plurality of pathways, 300 with each pathway corresponding toan arm 110 of the locking device 108. FIG. 3B shows that the base 104can define a plurality of such pathways, e.g., two or three pathwaysconfigured to receive corresponding arms 110. There can be four or morethan four pathways 300. The pathway 300 can have a first end located atthe opening or apertures 124 in the collar 220 or of the cylindricalmember 908. The pathway 300 can continue down through the base member104 or the low profile base member 104A. FIG. 3C shows that the pathway300 can have one or more segments disposed through the helical structure224. A first segment 300A of the pathway 300 extends from the aperture124 to a first portion, e.g., a proximal-most turn or portion of thehelical structure 224 immediately distal of the collar 220, e.g.,immediately distal of one of the apertures 124. A second segment 300B ofthe pathway 300 extends from the first segment 300A to a second turn orportion of helical structure 224 immediately distal of the first portionof the helical structure. A third segment 300C of the pathway 300 canextend from the second segment to a third turn or portion of helicalstructure 224 immediately distal of the second portion of the helicalstructure 224. The low profile base member 104A can have one or aplurality of, e.g., three, pathways 300 which can have segments asdescribed above.

FIGS. 3A and 3D illustrate that at specific locations along the lengthof the base 104 from the first end 204 to the second end 208, thepathway 300 can have a first boundary 304 corresponding to an outersurface or layer of the cylindrical portion 260, for examplecorresponding to a surface of the outer layer 268. The pathway 300 canhave a second boundary 308 at a same location along the length of thebase 104 from the first end 204 to the second end 208 formed by anadjacent portion of helical structure 224. The second boundary 308 caninclude a U-shaped opening in the inner portion 240 of the helicalstructure 224. The U-shaped opening in the inner portion 240 can extendacross the width of the helical structure toward the outer portion 244of the helical structure 224. The U-shaped opening can extend 25%, 35%,45%, 50%, 60%, 70%, 75% or up to 90% of the distance across the width ofthe helical structure 224 from the inner portion 240 toward the outerportion 244. In one embodiment, the helical structure 224 has a taperedconfiguration in which transverse distance between opposite sides of thehelical structure 224 is decreased in the direction of the first end 204compared to the same dimension toward the second end 208. The length ofthe U-shaped opening in successive portions of the helical structure 224in the direction toward the first end 204 is progressively less in someembodiments. As a result the width bounded by a turn of the helicalstructure 224 and the cylindrical portion 260 in the first segment 300Aof the pathway 300 can be greater than the width bounded by a turn ofthe helical structure 224 and the cylindrical portion 260 in the secondsegment 300B. The width in the second segment 300B can be greater thanthe width in the third segment 300C bounded by a turn of the helicalstructure 224 and the cylindrical portion 260. This configuration isadvantageous in accommodating embodiments of the locking device 108having arms 110 that are tapered as discussed further below.

The pathway 300 can extend through one or more spaces between adjacentthreads of the helical structure 224. The pathway 300 can comprise twoor more segments surrounded by portions of the base member 104 and atleast one exposed segment ES. The exposed segments comprise portions ofthe first and second segments 300A, 300B and between the second andthird segments 300B, 300C in some embodiment. The exposed segments ESare exposed in that, unlike the segments 300A, 300B, 300C, the exposedsegments of the pathway 300 are not enclosed circumferentially and thusbone disposed within the helical portion 224 can directly contact thearms 110 in the exposed segment. As such the pathway 300 is bounded bybone matter in the exposed segments.

FIGS. 2, 4 and 5 show the locking device 108 in detail. As discussedabove, the locking device 108 has a proximal support 132 and a first arm110 that projects distally of the proximal support 132. The proximalsupport 132 includes an inner periphery 358, an outer periphery 362 andan annular member 366 disposed therebetween. The inner periphery 358surrounds the central opening 136, which is sized to receive the innerraised portion 148 of the base member 104 if present. The annular member366 is configured to be received in the recess 140, as discussed above.

The first arm 110 is configured to be disposed in the first pathway 300.The pathway 300 projects distally of the collar 220. The first arm 110is disposed distal of the collar 220 when the proximal support 132 isdisposed adjacent to a proximal side of the collar 220 and the first arm110 is in the first pathway 300.

The first arm 110 includes an outer edge 370, an inner edge 374 and aspan 378 disposed therebetween. The first arm 110 includes a first end382 disposed away from the support 132 and a second end 386 disposedadjacent to and in some cases directly coupled to the support 132. Thefirst arm 110 can be tapered, for example with the outer edge 370approaching the inner edge 374 in the direction toward the first end 382and/or with the outer edge 370 diverging away from the inner edge 374 inthe direction toward the second end 386. In one embodiment, oppositefaces 390 of the span 378 are also tapered with at least one of, e.g.,both of, the opposite faces 390 approaching a longitudinal mid-plane Mof an arm 110. The tapering of the arms between the edges 370, 374facilitates providing a tapered profile in the base member 104. Thetapering of the arms between the edges 370, 374, sometimes referred toherein as a radial taper, facilitates insertion of the first end 382into the aperture 124 because the first end 382 is much narrower in thedimension between the edges 370, 374 than the aperture 124 is in theradial direction. The tapering of the arms 110 between the faces 390,sometimes referred to herein as a circumferential taper, facilitatesinsertion of the first end 382 into the aperture 124 because the firstend 382 is much narrower in the dimension between the faces 390 than theaperture 124 is in the circumferential direction.

At least one of the circumferential and radial tapers of the arms 110enables the locking device 108 to easily be advanced through bone matterthat is disposed along the pathway 300.

As discussed above, the first arm 110 is disposed through bone in thespace between successive portions of the helical structure 224, e.g., inthe first segment of the path 300 and in the second segment of the path300, when the humeral shoulder assembly is implanted. The span 378and/or other parts of the arms 110 can be porous to enhance bony ingrownwhen the assembly 100 is implanted. The porous properties can beprovided by a porous metal surface or structure or by other porouslayers disposed on an underlying layer of metal or another material. Atleast the widening of the arms 110 toward the second end 386 increasesthe purchase of bone in the widened area, e.g., in the first segment ofthe path 300 and also in the second segment of the path 300 compared toan arm that is not tapered.

In some embodiments, the arms 110 are not tapered in the radialdirection. For example the arms 110 can have a constant radial dimensionbetween the edges 370 and 374 at a length between, e.g., along theentire length between, the first end 382 and the second end 386. In someembodiments, the arms 110 are not tapered in the circumferentialdirection. For example the arms 110 can have a constant circumferentialdimension between the first end 382 and the second end 386.

As discussed above, the locking device 108 facilitates retaining thebase member 104 in the bone at least by opposing, and in some casescompletely preventing, rotation of the base member that would cause thebase member to back out of the bone into which it has been advanced.Additionally, in some embodiments, it is beneficial to oppose, and insome cases completely prevent, axial movement of the locking device 108away from the base member 104. At the extreme, such movement couldresult in the arms 110 of the locking device 108 completely coming outof the pathways 300 and, indeed, out of the base member 104 completely.It also may be desirable to prevent even lesser movements of the lockingdevice 108 relative to the base member 104. As shown in FIG. 6A, adistal face 402 of the annular member 366 may be positioned in directcontact with a proximal face 404 of the transverse flange 290. Suchcontact can correspond to a proximal face 406 of the annular member 366being distal of a proximal face 408 of the raised outer portion 152. Byrecessing the annular member 366, the interaction of the assembly 100with the articular member of the kit 80 of FIG. 1 is controlled. Forexample, the annular member 366 will not impede advancement of thearticular members into secure engagement with the recess 102.

FIGS. 5 and 6A illustrate various embodiments of axial lockingconfiguration that can be provided in the shoulder assembly 100. Anaxial locking configuration can include the engagement feature 164disposed on the proximal support 132. The spring arm 168 of theengagement feature can include a first end 420 disposed away from theannular member 366 and a second end 424 coupled with the annular member366. The spring arm 168 also has an elongate portion 428 that extendsbetween the first end 420 and the second end 424. The elongate portion428 preferably has an arcuate form and can, in some embodiments, havethe same curvature as a portion of the annular member 366 adjacent tothe second end 424. The elongate portion 428 can be separated from theannular member 366 along a radially inner edge 432 of the elongateportion 428 by a gap G. The gap G and the length of the elongate portion428 can be such that the first end 420 can be moved sufficiently toallow for a snap-fit connection as discussed further below. In oneembodiment, the first end 420 of the spring arm 168 has a deflector 436that facilitates movement of the elongate portion 428 and specificallymovement of the first end 420. FIG. 6A shows that the deflector 436 caninclude an angled surface 460 that initially engages a correspondingangled surface 464 on the base member 104, e.g., on the raised outerportion 152 at the proximal face of the base member. As the arms 110 ofthe locking device 108 are advanced into the paths 300, the annularmember 366 eventually is received in the space 294. At that time, theangled surfaces 460, 464 engage each other, which engagement causes thedeflection of the first end 420 of the spring arm 168. The first end 420is deflected radially inwardly such that the gap G is reduced at leastat the first end 420. This allows a proximal facing surface 472 to moveto a position distal of a distal facing surface 476. After the proximalfacing surface 472 is at a position distal of the distal facing surface476, the spring arm 168 resiliently moves the deflector 436 back to theconfiguration shown in FIG. 5. At this point, the proximal facingsurface 472 is distal of and aligned with, e.g., positioned under, thedistal facing surface 476, as shown in FIG. 6A. In this configuration,the proximal facing surface 472 blocks the distal facing surface 476from moving proximally. Thus the surfaces 472, 476 prevent the lockingdevice 108 from disengaging from the base member 104. Similar engagementbetween the locking device 108 and the low profile base member 104A canbe provided within the cylindrical member 908.

Another advantageous aspect of the assembly 100 is that the lockingdevice 108 can be quickly and easily disengaged from the base 104. Thetooling interface 158 allows an extraction tool to be disposed betweenthe raised outer portion 152 and the spring arm 168. The extraction toolcan apply a radially inward force on an outer periphery of the elongateportion 428 of the spring arm 168. Compression of the spring arm 168decreases the gap G as the proximal facing surface 472 is moved radiallyinward of the distal facing surface 476. Once the first end 420 isentirely radially inward of the distal facing surface 476, theengagement feature 164 is disengaged from the base 104. If more than onespring arm 168 is provided some or all of the spring arms can becompressed to allow the locking device 108 to be withdrawn from the base104. The shoulder assembly 100A can be disassembled in a similar mannerto remove the locking device 108 from the low profile base member 104A.

FIG. 6B shows additional axial locking configurations that can beprovided in the shoulder assembly 100. In these embodiments, axiallocking can occur at an interface 490 between one or more of the arms110 and one or more of the pathways 300. For example, the serrations 172discussed above can be provided at the interface. In one variation,serrations 172 are disposed along the pathway, e.g., on a surface of thecylindrical member 212 and/or on a surface of the helical structure 224.The serrations 172 can be placed at both the surface of the cylindricalmember 212 and at the helical structure 224. In another embodiment, theserrations 172 could be provided on a surface of the arm 110, e.g., onone of the outer edge 370, the inner edge 374, and/or on one of thefaces 390. The serrations 172 allow for relatively easy insertion of thearms 110 but bite into and oppose withdrawal of the locking device 108to oppose axial disengagement of the locking device 108 from the basemember 104. The locking device 108 can be secured to the low profilebase member 104A using the serrations 172 in a similar manner.

The serrations 172 can be disposed along the entire length of theinterface between the arms 110 and the base member 104 or just at aposition where the base member 104 and the locking device 108 are fullyengaged.

FIG. 2A shows a low profile shoulder assembly 100A that can be assembledfrom the low profile reverse kit 80A shown in FIG. 1C. The low profileshoulder assembly 82 can include a shoulder assembly 100A and a reverseinsert 96A. The reverse insert 96A can be selected from a plurality ofsuch inserts, such as following a determination of which insert providessufficient but not excessive tension in the soft tissue around theshoulder joint. For example, in one embodiment the low profile reversekit 80A can include a first reverse insert 96B-1 that has aninferior-superior height that is well suited for patients who havedistended or lax soft tissue around the shoulder joint such that it isuseful to position the humerus farther from the scapula during theprocedure. When first reverse insert 96B-1 is coupled directly with thecylindrical member 908 of the base member 104A a greater spacing isprovided between the resection plane and the scapula or between aprominence of the humerus (such as the greater tuberosity) and alandmark of the scapula (such as the acromion). The low profile reversekit 80A can include a second reverse insert 96B-2 that has aninferior-superior height that is less than that of the first reverseinsert 96B—1 and may be well suited for patients who have average softtissue around the shoulder joint such that it is useful to position thehumerus somewhat closer to the scapula during the procedure than wouldbe the case with the first reverse insert 96B-1. When the second reverseinsert 96B-2 is coupled directly with the cylindrical member 908 of thebase member 104A a spacing is provided between the resection plane andthe scapula or between a prominence of the humerus (such as the greatertuberosity) and a landmark of the scapula (such as the acromion) that isless than that provided by the first reverse insert 96B-1. The lowprofile reverse kit 80A can include a third reverse insert 96B-3 thathas an inferior-superior height that is less than that of the secondreverse insert 96B-2 and may be well suited for patients who haverestrictive or tight soft tissue around the shoulder joint such that itis useful to position the humerus somewhat closer to the scapula duringthe procedure than would be the case with the second reverse insert96B-2. When the third reverse insert 96B-3 is coupled directly with thecylindrical member 908 of the base member 104A a spacing is providedbetween the resection plane and the scapula or between a prominence ofthe humerus (such as the greater tuberosity) and a landmark of thescapula (such as the acromion) that is less than that provided by thesecond reverse insert 96B-2.

The low profile reverse kit 80A also can include a reverse insertassembly 96B-4. The assembly 96B-4 is configured to directly couple withthe cylindrical member 908 of the lower profile base member 104A. Theassembly 96B-4 can include a spacer 909 that is configured to directlycouple with the base member 104A, e.g., with an inside surface or wallof the cylindrical member 908 or in the recess 102 if the spacer isprovided with a tapered projection similar to the tapered projection 98.A reverse insert 96A is configured to directly couple with the spacer909. The spacer 909 and the reverse insert 96A can have a combinedinferior-superior height comparable to the first reverse insert 96B-1but can have the advantage of enabling part of the assembly 96B-4 to beof a more durable material than that of the insert 96A. The insert 96Acan be made of a polymeric material. The spacer 909 can be made of ametal, e.g., of titanium, stainless steel, or another biocompatiblemetal. The spacer 909 can be made of the same material as that used tomake the base 104A. The spacer 909 allows any of the inserts 96B-1,96B-2, 96B-3 to be adjusted to create greater space between thearticular surface thereof and the resection plane of the humerus suchthat greater tension can be induced in the soft tissue around theshoulder joint following surgery.

The low profile base member 104A includes many structures in common withthe base member 104. The base member 104A can be configured to becoupled with a locking device 108 to enable the base member 104A toretain its position in the humerus when implanted. In addition, the lowprofile base member 104A includes a submergible portion 900 and anexposed portion 904. The submergible portion 900 can include the helicalstructure 224. The low profile base member 104A can include acylindrical member 908. The cylindrical member 908 can be locatedopposite the helical structure 224, e.g., extending from the submergibleportion 900 into and in some cases to the inferior end of the exposedportion 904. In some embodiments the submergible portion 900 and aportion of the cylindrical member 908 closest to the helical structure224 can be configured similar to the base member 104 such that the sameor a similar method of implantation can be used for each of the basemember 104 and the low profile base member 104A.

The reverse insert 96A includes an articular portion 912 and a retentionportion 916. The articular portion includes a concave surface 920configured to articulate over a glenosphere 99. FIG. 18B shows that invarious advantageous embodiments the cylindrical member 908 and theretention portion are configured to provide for direct coupling ordirect connection between the reverse insert 96A and the low profilebase member 104A. The reverse insert 96A can be cylindrical. The reverseinsert 96A can be symmetrical, e.g., having the same height on aninferior and a superior portion of the reverse insert 96A. For example,the distance from an inferior end 913 of the retention portion 916 to asuperior end 914 opposite the retention portion 916 can be the same allthe way around an outer periphery 918 of the reverse insert 96A.

FIGS. 1C and 2A shows a shoulder assembly 100A in an exploded view. Theshoulder assembly 100A includes the low profile base member 104A and thelocking device 108 discussed above. The locking device 108 includes theproximal support 132 and the arms 110. The arms 110 project distally ofthe proximal support 132. The arms 110 can be positioned in the pathways300, projecting distally of the exposed portion 904 when the proximalsupport 132 of the locking device 108 is disposed within the cylindricalmember 908 in the exposed portion 904. As such the arms 110 can bedisposed through bone in the space between successive portions of thehelical structure 224 of the shoulder assembly 100A. The arms 110 can bepositioned radially inward of the outer periphery of the helicalstructure 224 when the locking device 108 is assembled to the lowprofile base member 104A.

The low profile base member 104A is generally tapered in the directionaway from the exposed portion 904 toward the end of the submergibleportion 900 opposite the exposed portion 904. In some embodiments, thearms 110 are also tapered, e.g., narrower toward the end opposite theproximal support 132.

The low profile base member 104A can include an inner core 147 which canbe the portion of the low profile base member 104A from which thehelical structure 224 extend. The inner core 147 can include thecylindrical portion 260. The helical structure 224 surrounds thecylindrical portion 260 and can surround the entirety of the inner core147. The cylindrical portion 260 extends distally from the exposedportion 904. The cylindrical portion 260 can include disposed therein atooling interface for connecting to an inserter to move the low profilebase member 104A into the surgical field and to cause the exposedportion 904 to be advanced into the humerus H.

The low profile base member 104A has an external surface 924 disposedbetween the submergible portion 900 and the exposed portion 904. Theexternal surface 924 can include a bone interface portion 926 and theexternal surface 924 can extend superiorly from the bone interfaceportion 926 to the superior end of the low profile base member 104A. Insome methods discussed further below the low profile base member 104Acan be advanced into the cancellous bone of the humerus H until thehelical structure 224 is fully submerged in the bone. The low profilebase member 104A can be advanced until at least a portion of the lowprofile base member 104A is at or below the resection surface of thehumerus H. The low profile base member 104A can be advanced until asurface within the cylindrical member 908 is at and in some casespartially inferior of the resection surface of the humerus H.

The cylindrical member 908 can include an inferior wall 930 and a raisedouter portion 156A. The raised outer portion 156A can include a sidewall 932. The side wall 932 can extend to an inferior end of the lowprofile base member 104A. The inferior wall 930 and the side wall 932bound a cylindrical space of the low profile base member 104A to whichthe reverse insert 96A can be secured as discussed further below. Theinferior wall 930 can have apertures for accessing the pathways 300, asdiscussed above. At the boundary of the inferior wall 930 and the sidewall 932 one or a plurality of tool interfaces can be provided as shown.The tool interfaces can be used to disengage the spring arm 168 (orother locking device) as discussed above.

FIGS. 16A and 16B shows variations on how the reverse insert 96A can besecured to the cylindrical member 908. FIG. 16A shows that aninterference connection can be provided between the reverse insert 96Aand the cylindrical member 908. In one embodiment, one or more ridges944 can be provided extending radially inwardly from an inner portion ofthe side wall 932. The ridge 944 can extend to a peak 948 disposedinward of the side wall 932. The reverse insert 96A can have an outerperiphery, e.g., an outer radius, that is larger than the dimensiondefined by the peaks 948. In inserting the reverse insert 96A into thecylindrical member 908 an interference fit can be provided between thereverse insert 96A and the cylindrical member 908 that securely holdsthe reverse insert 96A in the low profile base member 104A. Thecylindrical member 908 can be made of a material that is more rigid thanthe material used to make the reverse insert 96A. As a result theretention portion 916 of the reverse insert 96A can be compressed duringinsertion creating a strong connection between the reverse insert 96Aand the low profile base member 104A. One or a plurality of opening 950can be provided in the cylindrical member 908 to allow a tool to beinserted through the cylindrical member 908 into direct contact with theretention portion 916 to disengage the retention portion 916 from theside wall 932 of the cylindrical member 908.

FIG. 16B shows another embodiment in which a C-ring 952 is provided formechanically and more easily releasably coupling a reverse insert 96Bwith the low profile base member 104A. The C-ring 952 can becompressible such that upon initial insertion of the reverse insert 96Binto the cylindrical member 908 the C-ring 952 is compressed to asmaller diameter. When compressed the reverse insert 96B can slide alongthe side wall 932 until the reverse insert 96B reaches the inferior wall930. When the inferior end of the retention portion 916 is at oradjacent to the inferior wall 930 the C-ring 952 expands into anenlarged channel 954 disposed in the side wall 932. When in the enlargedchannel 954 the C-ring 952 has superior surface that overlap with aninferior-facing surface 956 of the enlarged channel 954. As such theenlarged C-ring 952 blocks the reverse insert 96B from being removedfrom the cylindrical member 908. The C-ring 952 can be easily compressedfor removal by inserting a tool into the openings 950 as discussedabove. In one embodiment there are four openings 950 which can be spaced90 degrees apart from each other.

In some embodiments structures can be provided to rotationally fix thereverse inserts 96A, 96B within the low profile base member 104A. Insome embodiments one or more anti-rotation features 960 are provided tolimited, reduce or eliminate rotational motion of the reverse insert96A, 96B within the low profile base member 104A. The anti-rotationfeatures 960 include a plurality of discrete spaced apart engagementstructures that can engage the outer periphery 918 of the reverse insert96A. The anti-rotation features 960 can include, for example, radialbarbs 964 which can be in form of radially projecting and ridges thatare aligned with a superior-inferior direction. As such the radial barbs964 can extend directly into a side surface of the retention portion916. The radial barbs 964 can be dispersed equally around the side wall932, e.g., 60 degrees apart from each other. A plurality of radial barbs964 can be at other positions, e.g., at 30 degrees, 40 degrees or 50degrees from each other.

II. Method of Application to an End Portion of a Long Bone

FIGS. 8-16 illustrate various techniques for implanting the shoulderassembly 100 in a humerus H. The method illustrates placement in aproximal end of the humerus H, e.g., in the humeral head h.

FIG. 8 illustrates an early step of one embodiment of a method includingresecting the head h of the humerus H. Prior to resecting the head h ofthe humerus H a guide 600 is applied to the humerus H. The guide 600includes structure for mating with the humerus H and the head h, forexample, a plate 604 to mate with the humerus H and pins 608 to matewith the head h. The guide 600 also has a slot 612 to guide a saw to cutthe humerus H to expose cancellous bone of the head h. FIG. 9 shows thatafter resecting the head h of the humerus H the size of the head isevaluated with a template 620. To obtain a quick and accurate sizing, aguide pin 624 is first placed in the resected head h. The template 620is advanced over the guide pin 624 into contact with the resected head.The size of the resected head h is determined from the template 620. Theguide 600 can be a reusable guide that is not specific to any particularpatients. In other embodiments, the guide 600 is formed with referenceto a specific patient. That is, the guide 600 can be formed to mate withthe patient, such as by conforming in whole in part on a bone facingside to the shape of the bone as observed or measured using imaging orother devices prior to surgery.

FIG. 10 shows that the resected surface of the head h can be prepared,such as by using a planar or a reamer 632. The reamer 632 also can beguided by the guide pin 624. The reamer 632 can be used to form arecessed surface s to which the assembly 100 will be applied afterfurther preparation.

FIG. 11 shows a step of measuring depth of the recessed surface s. Thepurpose of this step is to provide a secondary confirmation that theassembly 100 will fit into the metaphysis without striking the lateralcortex. While the analysis of FIG. 9 indicates a diameter of base member104 that could be used, the depth gauge 637 of FIG. 11 provides a depthsizing that confirms a maximum length, e.g., depth, that would fit inthe recessed surface S surgeon is instructed to take the smaller of thetwo sizes determined.

FIG. 12 illustrates that following depth measurement, a bore b is formedin the surface s in initial preparation of the surface s to receive theshoulder assembly 100. The bore b is formed using a drill 640. The drill640 can be a convention cannulated design configured to be advanced overthe guide pin 624. The drill 640 can be configured as a universal drillwith a modular stop to obtain variable lengths. The drill 640 can be oneof a plurality of drills, each drill of the plurality having a differentsize as appropriate. In certain methods, the process of forming the boreb and reaming the surface s as discussed above in connection with FIG.10 can be combined. For example, a drill 640 can have a reaming featuredisposed proximally of the bore forming features such that a continuousmotion toward the surface formed using the guide 600 can initially formthe bore b and subsequently form the surface s. FIG. 13 shows that oncethe bore b has been formed, the bore b can optionally be tapped to beprepared to receive the base member 104 of the shoulder assembly 100.The tapping process can be achieved by using a helical tap component 648that is advanced over the guide pin 624. The helical tap 648 can followthe form of the helical structure 224 of the base member 104 such thatthe base member 104 can be easily advanced into the bore. The helicaltap 648 can be secured to a shaft 654 that can be mounted to a motordriven drill or to a hand tool.

FIG. 14 shows a step of inserting the base member 104. The base member104 is secured to a distal end of an inerter 662. The inserter 662 has astem 666 that is threaded at a distal end thereof. The threads of thestem 666 can be mated with the tool interface 272 (see FIG. 7), e.g.,with threads of the tool interface. Preferably the stem 666 is enlargedat a mid-section thereof providing at least a shoulder that can matewith the inner raised portion 148 of the base member 104. A separatemember 668 of the inserter 662 is advanced over the stem 666 to the toolinterface 158, and the force of advancing the base member 104 thus canbe applied through the tool interface 272, through the inner raisedportion 148, through the apertures 124 or through more than one of these(or other) features of the base member 104. Splines 672 provide for goodgrip by the surgeon so that the surgeon can easily engage the stem 666to the tool interface 272. In another variation, a driver with atorqueing device at a proximal end couples at its distal end directlywith the tool interface 272, through the inner raised portion 148,through the apertures 124 or through more than one of these (or other)features of the base member 104 to enable more direct transfer of torqueto the base member. Preferably inserting the base member 104 into thebone includes placing the outer periphery 154 in the recessed surface s,e.g., at least partially recessed into the resected bone of the humerusH.

FIG. 14A shows that the low profile base member 104A can be advancedinto the humerus H in the same manner as the base member 104.Specifically, the surface s can be formed, recessed into the humerus H.The bore b can be formed in the humerus H extending inferiorly from thesurface s. The low profile base member 104A can be advanced inferiorlyas indicated by the arrow 970. As shown in FIG. 14, the inserter 662 canbe coupled with the low profile base member 104A. The stem 666 can beinserted into the recess 102 to abut to an inner raised portion 148 ifprovided. The stem 666 can provide for handling and initial placement ofthe first end 204 into the bore b. The stem 666 or the member 668advanced over the stem 666 can be used to advance the low profile basemember 104A into the bore b by engaging the helical structure 224 to thecancellous bone around the bore b. The low profile base member 104A cancontinue to be advanced until the bone interface portion 926 is disposedin the bone, e.g., in the position shown in FIG. 7A.

Following placement of the low profile base member 104A in the resectedportion of the humerus H the locking device 108 can be advanced in themanner shown in FIG. 15. The locking device 108 can be advanced over thestem 666 into the cylindrical member 908. The locking device 108 can beadvanced inferiorly of the side wall 932, for example to a positionbetween anti-rotation features 960 and the inferior wall 930, to aposition between the interface 936 and the inferior wall 930, to aposition at the base of the side wall 932, or to a position between theside wall 932 and the inferior wall 930.

After the locking device 108 is secured to the low profile base member104A, an articular insert can be directly coupled with the cylindricalmember 908. In other words, following the step of the procedureillustrated in FIG. 15, the reverse insert 96A can be directly coupledwith the cylindrical member 908 without the need to couple the tray 94with the recess 102. The reverse insert 96A can be advanced into thecylindrical member 908 and urged under a force into an interferenceengagement with the cylindrical member 908. The process can result insome deformation or at least compression of the retention portion 916within a radially smaller zone of the side wall 932, e.g., within theridge 944. The reverse insert 96B can be inserted until the C-ring 952engages a portion of the cylindrical member 908. The cylindrical member908 can have an angled face that can engage a corresponding angled faceof the C-ring 952. Such engagement can cause, by a wedge action, theC-ring 952 to be compressed to allow the reverse insert 96B to furtheradvance until the C-ring 952 is disposed in the enlarged channel 954.When in the enlarged channel 954 the C-ring 952 can engage theinferior-facing surface 956 to secure the reverse insert 96B in thecylindrical member 908 of the low profile base member 104A.

FIG. 15 shows that after the base member 104 has been inserted, thelocking device 108 can be inserted. The base member 104 is inserted by arotation of the member by rotation of the inserter which is directlyconnected to the base member as discussed above in connection with FIG.14. The locking device 108 is inserted along the pathway by lineartranslation, e.g., by a movement along a generally straight axis withoutrotation. An inserter 680 is provided that has an enlarged head 682 thatcan be secured to or can just rest upon the proximal face of the annularmember 366 of the proximal support 132. The head 682 is then advancedover the splines 672 of the stem 666, with the stem 666 acting as anaxial guide. In order to implant the locking device 108 the first end382 of the arm 110 or arms is aligned with the aperture 124 or aperturesif more than one. The arms 110 are radially and circumferentiallytapered and the apertures 124 are sized for the wider proximal end ofthe arms. This configuration helps guide the locking device 108 into thebase member 104. The proximal end 684 of the inserter 680 in configuredfor impacting the locking device 108 into the base member 104.

FIG. 16 shows later steps of a method of implanting an anatomic shoulderprosthesis. After the base member 104 and the locking device 108 areplaced, an anatomic articular component 84 can be coupled with therecess 102. The anatomic articular component 84 comprises a convexsurface 90, analogous to the natural anatomy. The anatomic articularcomponent 84 is placed with an impactor 684A. Although shown as aseparate, dedicated device the insertion and impaction functionsillustrated in FIGS. 15 and 16 could be carried out by the same device.For example a contoured face to contact the surface 84 could have aportion configured for inserting the locking device 108 and/or the tray94. FIG. 16 shows an alternative step of a method of implanting areverse shoulder prosthesis. After the base member 104 and the lockingdevice 108 are placed, a reverse articular component 88 can be coupledwith the recess 102. In one form, the reverse articular component 88includes a tray 94. The tray 94 can be coupled with an articularcomponent 96 comprising a concave surface for articulating with aglenoid sphere disposed on a glenoid of a scapula (discussed furtherbelow). The tray 94 is placed with an impactor 684A. The reverseshoulder prosthesis including the shoulder assembly 100, the tray 94 andthe articular component 96 is shown in FIGS. 18 and 18A. A glenoidsphere 99 mated with a glenoid is shown in FIG. 18A. The shoulder jointprovides movement of the patient's arm by articulating the component 96over the glenoid sphere 99.

In one variation of these methods, assemblies, and kits the lockingdevice 108 is inserted at the same time as some or all of the reversearticular component 88 or at the same time as the anatomic articularcomponent 84. The locking device 108 can be a separate component that isloaded onto an inserter or impacting tool that can be previously loadedwith the reverse articular component 88 or the anatomic articularcomponent 84. The locking device 108 can be a separate component that isloaded onto an inserter or impactor with, but relatively moveable to,the reverse articular component 88 or the anatomic articular component84. The locking device 108 and the reverse articular component 88 can beformed as a monolithic structure that can be loaded together onto aninerter. The locking device 108 and the anatomic articular component 84can be formed as a monolithic structure that can be loaded together ontoan inerter.

III. Advantages and Performance of Embodiments Disclosed Herein

FIGS. 18A and 18B illustrate advantages of the low profile base member104A and the shoulder assembly 100A that can be formed therefrom. Asdiscussed above, the low profile base member 104A facilitates a lowprofile shoulder assembly. The result is that the surgeon is given morecontrol over the position of the various components of the shoulderassembly and over the degree of tension in soft tissue around theshoulder joint following the procedure. This has several importantbenefits. The shoulder assembly 100 has a first profile height H₁. Thefirst profile height H₁ is a maximum height dimension of the shoulderassembly 100 as measured from the first end 204 to the superior end 97of the insert 96 coupled with the base member 104. The first profileheight H₁ can be seen to be much larger than the second profile heightH₂, which is measured from the first end 204 of the low profile basemember 104A to the superior end 914 of the reverse insert 96A. Acorrespondingly smaller dimension can be provided from the first end ofthe low profile base member 104A to the inferior portion of thearticulation portion 912 that is provided from the first end of the basemember 104 to the inferior portion of the articulation portion thereof.As a result the resected humerus can be positioned farther away from theglenoid at the same or lesser soft tissue tension than the shoulderassembly 100 including the base member 104.

FIG. 18C shows further advantages of a shoulder assembly 100A-1 that canbe formed using the spacer 909. As discussed above, the spacer 909 canbe provided in a kit with other component discussed herein. For apatient requiring more spacing between the articular surface of areverse shoulder insert and a resection plane of a humerus a largerinsert (such as the first insert 96A-1) can be provided. If more spacingis required, the spacer 909 can be combined with the first insert 96A-1to further increase the spacing between the articular surface of areverse shoulder insert and a resection plane of a humerus. Byincreasing the spacing between the articular surface of a reverseshoulder insert and a resection plane of a humerus soft tissue that aredistended or lax can be tensioned following surgery. The shoulderassembly 100A-1 can be provided by initially embedding the submergibleportion 904 of the base 104A in the cancellous bone at and inferior ofthe resection plane. Thereafter, the spacer 909 can be secured in thecylindrical member 908. The spacer 909 can be coupled in any suitableway, such as using the structures illustrated in FIGS. 16A and 16B. Theimpactor 684A can be used to urge the spacer 909 into a lockedconfiguration within the cylindrical member. In an alternativeembodiment not illustrated the spacer 909 can have a tapered stemportion that is adapted to be received in the recess 102 of the basemember 104A. After the spacer 909 is secured directly to the cylindricalportion 908 or in the recess 102 the reverse insert 96A is secured tothe spacer 909. The spacer 909 can have a cylindrical superior portionwithin an interior wall having the same configuration as that of thecylindrical portion 908. Thus the reverse insert 96A can be secured tothe superior portion of the spacer 909 as illustrated in FIGS. 16A and16B.

FIGS. 19A and 19B show comparative performance of embodiments disclosedherein with respect to a stemless apparatus that does not have thehelical structures disclosed herein nor the locking devices. The graphin FIG. 19A shows average pull out force which is measured by a loadopposite of the direction of implanting the base member 104. FIG. 19Bshows average lever out force which is measured by applying an off axisload at a known or prescribed fixed distance from a surface at or towhich a shoulder assembly similar to the assembly 100 was implanted. Thetip out force represents the resistance of the device to tipping out orbecoming dislodge from the surface when subject to off axis loading. Theforces were observed using a load cell or force transducer. As can beseen, the force of one embodiment is more than four times the force thatwould dislodge the conventional stemless component. This represents asignificant improvement in the retention of the apparatuses disclosedherein compared to conventional stemless design which rely to a largeextent on ingrowth for securement which can be sufficient some timeafter implantation but which can be subject to dislodgement prior tofull integration by ingrowth. The inventors expect that the assembly100A will have performance that is at least as good as that illustratedin FIGS. 19A and 19B.

As used herein, the relative terms “proximal” and “distal” shall bedefined from the perspective of the humeral shoulder assembly. Thus,distal refers the direction of the end of the humeral shoulder assemblyembedded in the humerus, while proximal refers to the direction of theend of the humeral shoulder assembly facing the glenoid cavity when theassembly is applied to the humerus. Distal refers the direction of theend of the humeral shoulder assembly embedded in the scapula, whileproximal refers to the direction of the end of the humeral shoulderassembly facing the humerus when the assembly is applied to the glenoid.In the context of a glenoid component, the distal end is also sometimesreferred to as a medial end and the proximal end is sometimes referredto as a lateral end.

Conditional language, such as “can,” “could,” “might,” or “may,” unlessspecifically stated otherwise, or otherwise understood within thecontext as used, is generally intended to convey that certainembodiments include, while other embodiments do not include, certainfeatures, elements, and/or steps. Thus, such conditional language is notgenerally intended to imply that features, elements, and/or steps are inany way required for one or more embodiments or that one or moreembodiments necessarily include logic for deciding, with or without userinput or prompting, whether these features, elements, and/or steps areincluded or are to be performed in any particular embodiment.

The terms “approximately,” “about,” and “substantially” as used hereinrepresent an amount close to the stated amount that still performs adesired function or achieves a desired result. For example, the terms“approximately”, “about”, and “substantially” may refer to an amountthat is within less than 10% of, within less than 5% of, within lessthan 1% of, within less than 0.1% of, and within less than 0.01% of thestated amount. As another example, in certain embodiments, the terms“generally parallel” and “substantially parallel” refer to a value,amount, or characteristic that departs from exactly parallel by lessthan or equal to 15 degrees, 10 degrees, 5 degrees, 3 degrees, 1 degree,0.1 degree, or otherwise.

Some embodiments have been described in connection with the accompanyingdrawings. However, it should be understood that the figures are notdrawn to scale. Distances, angles, etc. are merely illustrative and donot necessarily bear an exact relationship to actual dimensions andlayout of the devices illustrated. Components can be added, removed,and/or rearranged. Further, the disclosure herein of any particularfeature, aspect, method, property, characteristic, quality, attribute,element, or the like in connection with various embodiments can be usedin all other embodiments set forth herein. Additionally, it will berecognized that any methods described herein may be practiced using anydevice suitable for performing the recited steps.

For purposes of this disclosure, certain aspects, advantages, and novelfeatures are described herein. It is to be understood that notnecessarily all such advantages may be achieved in accordance with anyparticular embodiment. Thus, for example, those skilled in the art willrecognize that the disclosure may be embodied or carried out in a mannerthat achieves one advantage or a group of advantages as taught hereinwithout necessarily achieving other advantages as may be taught orsuggested herein.

Although these inventions have been disclosed in the context of certainpreferred embodiments and examples, it will be understood by thoseskilled in the art that the present inventions extend beyond thespecifically disclosed embodiments to other alternative embodimentsand/or uses of the inventions and obvious modifications and equivalentsthereof. In addition, while several variations of the inventions havebeen shown and described in detail, other modifications, which arewithin the scope of these inventions, will be readily apparent to thoseof skill in the art based upon this disclosure. It is also contemplatedthat various combination or sub-combinations of the specific featuresand aspects of the embodiments may be made and still fall within thescope of the inventions. It should be understood that various featuresand aspects of the disclosed embodiments can be combined with orsubstituted for one another in order to form varying modes of thedisclosed inventions. Further, the actions of the disclosed processesand methods may be modified in any manner, including by reorderingactions and/or inserting additional actions and/or deleting actions.Thus, it is intended that the scope of at least some of the presentinventions herein disclosed should not be limited by the particulardisclosed embodiments described above. The limitations in the claims areto be interpreted broadly based on the language employed in the claimsand not limited to the examples described in the present specificationor during the prosecution of the application, which examples are to beconstrued as non-exclusive.

What is claimed is:
 1. A method of implanting a prosthesis, comprising: advancing by rotation a base member, comprising a cylindrical member and a helical structure, into a resection face of a humerus of a patient such that the helical structure is submerged in and engages cancellous bone of and does not extend distally of an epiphysis of the humerus, the cylindrical member being accessible at the resection face of the humerus when the base member is so advanced; advancing a locking device into the base member until at least one elongate member spans a space between adjacent portions of the helical structure to contact the cancellous bone in the space; and inserting a retention portion of a reverse articular insert into the cylindrical member of the base member to directly connect the reverse articular insert with the cylindrical member of the base member.
 2. The method of claim 1, wherein advancing the locking device comprises linearly translating the elongate member of the locking device into the space.
 3. The method of claim 1, wherein inserting the retention portion comprises providing an interference fit between the retention portion of the reverse articular insert and the cylindrical member to secure the reverse articular insert against at least one of dislodgement or rotation.
 4. The method of claim 1, wherein advancing the base member by rotation involves rotating the base member in a direction such that the helical structure threads into the resection face of the humerus.
 5. The method of claim 1, further comprising a step of forming a bore in the resection face of the humerus, wherein the bore is sized to receive the helical structure of the base member. 